Needle cylinder assembly for knitting machines



A ril 16, 1968 'J. J. MCDONOUGH NEEDLE CYLINDER ASSEMBLY FOR KNITTINGMACHINES 2 Sheets-Sheet 1 Filed Feb. 16, 1966 F l G.

INVENTOR JOHN J. McDONOUGH Z 7 7 AMA ATTORNEYS April 16, 1968 J. J.MODONOUGH 7 3,

NEEDLE CYLINDER ASSEMBLY FOR KNITTING MACHINES Filed Feb. 16, 1966 2heets-Sheet 2 FIG. 3. INVENTOR JOHN J. MCDONOUGH ATTORNEYS United StatesPatent 3.377,823 NEEDLE CYLINDER ASSEMBLY FOR KNITTING MACHINES John J.McDonough, Laconia, N.H., assignor, by mesne assignments, to Scott &Williams, Inc., Laconia, N.H., a corporation of Delaware Filed Feb. 16,N66, Ser. No. 527,993 4 Claims. (Cl. 66115) ABSTRACT OF THE DISCLOSURENeedles are maintained in accurate relationship to each other and tosinkers by a slotted ring located above the upper ends of the needlecylinder slots, and supported against movement in an axial direction bya wear ring and by horizontal projections of the sinkers. The slottedring is not secured to any other part of the needle cylinder assembly,but its circumferential and radial positions are maintained solely bythe locations of the needles in its slots.

This invention relates to a needle cylinder assembly for knittingmachines and particularly to the provision of means located at the topof the needle cylinder to provide accurate location of the needles bysupport thereof at as high a level as possible.

Circular knitting machines for ladies seamless hosiery involve extremeprecision in construction to provide corresponding precision in theuniformity of the fabric produced. Typically, such hosiery involvesknitting of synthetic monofilament yarns of denier, or correspondingmultifilament yarns, having cross-sectional diameters of less than 0.002inch. Four hundred or more latch needles having thicknesses of 0.013inch, or less, reciprocate in closely spaced slots in cylinderstypically of 3% inch diameter or less. A complementary sinker ringhaving slots corresponding in number tothe needles provides for spacingof sinkers which are essentially equidistant for adjacent needles.

Very minute deviations in stitch sizes or symmetry adversely aifectvtheappearance of the fabricQWhile the deviation involved in a single stitchmight not be noticeable, when a group of corresponding stitchesextending walewise in the fabric involve similar deviations, the effectis the production of vertical streaks which are easily noticeable, theeffect being that of producing a vertical panel in the fabric having adensity differing from that of adjacent portions of the fabric. Manyfactors may contribute to the production of such streaks. Nonuniformityof needles is one of these, correctible only by precision in needlemanufacturing which is attainable despite the minute dimensionsinvolved. Other factors, however, involve various deviations in therelative locations of needles with respect to each other and withrespect to associated sinkers. While high precision in the spacing ofneedle slots may be achieved, one trouble inherent in the usual machinesis that due to structural arrangements which are required, particularlyfor the guidance of sinkers, considerable lengths of the needles projectwithout adequate circumferential guidance above the cylinder slots, anddue to the small thicknesses of the needles circumferential deviationsof their positions may occur resulting in variations in theirrelationships to adjacent sinkers. The sinkers themselves are far morerigid than the needles and are guided both exteriorly and interiorly ofthe needle circle, and the sinkers may be very accurately formed andgenerally do not in themselves contribute to the irregularities inneedle-sinker relationships.

The general object of the invention may be stated to be the provision ofproper and accurate support of the upper portions of the needles tomaintain them in accurate relationship to each other and to the sinkers.In accordance with the invention, needle guidance is effected throughthe use of a slotted ring which is floating in the sense that it is notsecured to other parts of the needle cylinder assembly. Its dimensionsare small and itmay be very accurately slotted for reception of theneedles, and its accuracy is not impaired by the application of stresseswhich would be involved in securing it rigidly to the cylinder assembly.In effect, it is located by the needles themselves, and particularly bythe average condition of the total group of needles so that any needleor needles of any small group tending to deviate from the others areforced to positions locating them in proper needle-toneedlerelationships.

The achievement of this general object and of other objects relating todetails of construction and operation will become apparent from thefollowing description, read in conjunction with the accompanyingdrawings, in which:

FIGURE 1 is an axial section taken through a needle cylinder assemblyand showing a typical needle and associated sinker in positionscorresponding to knockover;

FIGURE 2 is a view similar to FIGURE 1 but showing the needle at clearheight and the sinker partially withdrawn; and

FIGURE 3 is a plan view partly in section of a segment of the topassembly of the cylinder.

Most of the structure involved in connection with the invention isconventional. The needle cylinder 2 may be rotary or stationary, thoughfor consistency of description it may be considered rotary as is usualin modern machines. Walls 4 are inserted in slots 6 in the needlecylinder to define slots in which the needles 8 reciprocate vertically.The formation of a slotted needle cylinder by the insertion of walls iswell known and leads to high precision in the indexing of the needleslots. In the final formation of the cylinder the accuracy of the slotsmay be checked and uniformity may be achieved by slight deviations ofthe walls. The needles are held in the slots by one or more spring bandsindicated at 10 with location of the lower ends of the needles from aradial standpoint by the cam assembly acting on their usual butts (notshown). The needles are provided with the usual hooks 12 with whichcooperate the latches 14 pivoted to the needle shank structures at 16.

Because of the sinker-supporting structures involved the inserted wallsmust terminate at a level typically as at 18. FIGURE 1 shows a needle inWhat is ordinarily its lowermost knockover position, and it will be seenthat even in this position a considerable portion of the needle extendsabove the level at 18. The condition of non-support of the needle ismuch worse when it is in cleared position as indicated in FIGURE 2. Itwill be evident that v if the lateral support of the needle terminatedat 18 a needle which was bent could well have its critical portiondeviating quite considerably from what would be proper and achieved by astraight needle. The most critical portion of a needle from thestandpoint of stitch shape or location is the portion running from thehook down to the position of the open latch, though even the portion ofthe shank below an open latch may contribute to irregularity in theformation of stitches.

Continuing the matter of the structural assembly involved, a sinker ring20 is provided, mounted on portions of the inserted walls 4. The sinkerring is accurately slotted radially at 22 to provide support andguidance for the outer ends of the sinkers 24 which are provided withactuating butts 26 operated on by conventional cams. The sinkersthemselves may be of many forms for dilferent purposes as Well known inthe art, typically involving nebs 28 which extend inwardly over ledges30 over which stitches are ordinarily drawn and retained, "though thedrawing of stitches may be, as is known, over or behind sinker nebs. Aso-called cylinder top is provided at 32, and this has a flange portion33 to be secured adjustably and accurately to the top of the needlecylinder through the medium of screws inserted in tapped holes 35 andthrough slots 37. Such type of attachment is well known and serves forfine adjustment of the cylinder top both circumferentially andangularly, the adjustment being essentially of a universal type. Slots34 in this cylinder top receive the inner portions of the sinkers 24 andserve to align them uniformly circumferentially.

The vertical positions of the sinkers in the vicinity of the needlesmust be accurately maintained, and for this purpose it has beencustomary to secure to the cylinder top a wear ring 38 of hardened steelor some other very hard wear-resisting material. This ring actually hastwo functions: that of maintaining the vertical positions of thesinkers, and that of maintaining the upper ends of the needles indefinite radial positions. The first function is performed by thehorizontal, unslotted surface 38 of the ring, this surface providing aplatform on which the edges 42 of the sinkers may slide, the edges 42being provided by the upper boundaries of the notches 40 in the innerends of the sinkers. The surface 38 is slightly above the bottoms of theslots 34 in the cylinder top. The sinker edges 42 are accuratelystraight in the arrangement shown and are accurately related to thesinker ledges 30 to define the level over which loops are drawn.

The cylindrical outer surface 39 of the ring 36 provides a backing forthe needles locating their upper ends radially.

The lower boundaries 44 of the notches 40 in the sinkers are horizontaland accurately related to the edges 42. These edges 44 clear the uppersurface bounding the groove 46 in the cylinder top. No provision need bemade to prevent the sinkers from rocking upwardly because they are helddownwardly by the fabric during knitting, their vertical position beingthen determined solely by the surface 38 of the wear ring.

The construction so far described is conventional, but it will beevident that it does not provide lateral (circumferential) restraint onthe needles above the upper ends 18 of the inserted cylinder walls. Ithas been proposed to provide the wear ring 36 with radially extendingslots in which the needles are guided (Patent 2,154,384). Thisexpedient, however, has not been satisfactory for several reasons: thewear ring 36 must be tightly secured to the cylinder top and its slotsprovided as just mentioned must be very accurately related to the slots34 in the cylinder top. In view of the large number of slots required,it is not practical to maintain accurate relationship throughout thecircumference, and in some region it is substantially inevitable thatthere would not be undesired deviations from a proper relationship;secondly, it will be evident that the pivot of the latch and the portionof the needle slotted for movement of the latch would be obliged to movewithin the slots in the wear ring during operation as indicated inFIGURE 1. Since this region of the needle is very difficult to hold to aclose dimensional tolerance the slots would necessarily be suflicientlywide to provide smooth and free movement for the thickest needle whichwould be involved, the result being that for some needles there would besubstantial play.

In accordance with the present invention needle guidance is provided bya ring 48 provided with slots 50 in which the needle move, the ring 48being located below the wear ring 36 with a vertical clearance 52between it and the Wear ring and with a circumferential clearance 54between it and the cylinder top. The ring 48 is supported on the edges44 of the sinkers.

So far as this relationship to elements rigidly connected to thecylinder is concern ill? ring 48 is float ing, i.e., it is completelyunrestrained by these, and in the absence of needles would have freecircumferential and radial movements. Thus there exists no placement independence on the parts mentioned and, in particular, no stresses areimparted thereto by connections, which stresses might involve someasymmetry of its shape. The ring, having small thickness, may have itsslots very accurately indexed about its circumference. From FIG- URE 1it will be noted that the top of the ring 48 is at all times below thelatch pivot 16 of a needle, and therefore located within the slots 56are only portions Of needles which may be held accurately to thicknessdimensions. The slots 50 may, therefore, be larger than the needlethickness only by a small dimension involving the minimum clearance forfree sliding movement.

While the ring 4-8 is floating with respect to the parts secured to theneedle cylinder, its position is nevertheless maintained very accuratelyby the needles themselves. Assuming that the majority of the needles areproperly spaced, when the assembly is made, the slots 50 beingaccurately indexed, it will be evident that those needles which mightordinarily deviate from proper angular relationship will be sprung intoa uniform angular relationship. The condition which maintains theposition of the ring 48 is thus dependent on what might be consideredthe majority of the needles. While there is a clearance 54 and merelyviewing FIGURE 1 it might seem that the ring 48 could move to the rightor left as viewed in the plane of that figure, giving consideration to agroup of needles spaced from that shown it will be evident that suchgroup of needles will prevent the possibility of the movement justreferred to, i.e., it could not occur except with flexure of a largenumber of needles which, being reasonably guided by the cylinder wallsare not free to flex to any appreciable extent. In summary, the ring 48is thus quite fixedly, though theoretically flexibly, maintained indefinite position, with its primary achievement being the maintenance ofall of the needles in accurate circumferential relationship to eachother. It is this relationship to each other and uniform relationship tothe sinkers which is important. While elforts are ordinarily made toinsure, particularly by adjustment of the sinker top, that the sinkersare uniformly spaced from the needles which flank them, this is actuallynot highly important. Even if all of the sinkers, evenly spaced fromeach other, were shifted slightly relative to the needles so that theywere closer to a needle on one side than to the needle on the otherside, this circumferential asymmetry would affect all stitches in thesame fashion, and while the stitches might be slightly asymmetrical,there would be no difference in stitch sizes along the circumference andstreaks would not be noticeable in the fabric. This implies, of course,that the spacings between the sinkers and needles are always such as toavoid pinching of yarn, rubbing of latches, and the like.

The fact that guidance of the needles is substantially above the level18 prevents lateral deflections, being particularly effective when theneedles are in the most critical position of knockover which correspondsto the measuring of the drawn loops. Uniformity of fabric is thusachieved with a minimizing of highly critical adjustments, there being,of course, none required as between the floating ring 48 and the needleslots of the cylinder.

It will be evident that various changes in details of construction maybe made without departing from the invention as defined in the followingclaims.

What is claimed is:

1. A needle cylinder assembly for a fine gauge circular knitting machinecomprising a plurality of independently movable needlescircumferentially arranged, latches on said needles, pivots pivotingsaid latches on said needles, a needle cylinder providing slots for theguidance of shanks of said needles, means retaining the needles in saidcylinder slots, a plurality of sinkers, means fixed to the needlecylinder and slotted for the radial guidance of said sinkers, a slottedfloating ring unrestrained by any fixed connection to the needlecylinder or sinker guiding means, the slots in said ring being radialand arranged to receive the upper portions of the needles guided in thecylinder slots, and means supporting said ring against movement in anaxial direction and at a level at which the upper ends of its slots areapproximately at the level attained by said pivots of the needle latchesduring knockover, the circumferential and radial positions of said ringbeing maintained solely by the locations of the needles in its slots.

2. An assembly according to claim 1 in which the slots References CitedUNITED STATES PATENTS 8/1937 Lawson eta1.

4/ 1939 Richter 66-107 ROBERT R. MACKEY, Primary Examiner.

